Manufacture of alloys



UNITED STATES may rirvmes'rona sumum am) PATENT OFFICE.

WILLIAM BOWMAN BALLANTINE, OF LONDON, ENGLAND.

MANUFACTURE OF ALLOYS.

Io Drawing.

To all whom it mag concern Be it known that we, HENRY LIVINGS'IONB SULMAN and WILLIAM BOWMAN BALLAN- 'rma, subjects of the King of England, both residing at London, England, have invented certain new and useful Improvements in the Manufacture of Alloys, of which the following is a specification.

This invention relates to improvements in the manufacture of alloys, and is a modification of the process which consists in adding to a mixture of compounds of the metals to be alloyed, such, .for example, as oxids, a quantity of aluminium powder or other thermo-reducing agent and igniting the mixture toreduce the compounds to metallic form.

According to the present invention the process for the production of alloys by a method of the kind described,- comprises the employment of compounds, for example, oxids, of the metals, or of. certain of them, required in the alloy, these compounds bein in chemical combination with each ot er. 7

According to a modification of the present invention, any extra quantity of one of the com unds, above that which is in chemical com ination with the other compound, is added in combination with another metal of the alloy, for example, the preponderating metal of the alloy, or, in order to secure the desired proportion in the alloy of any.

metal in excess of that obtainable by combination -with another metallic compound, the addition may be made of a suitable derivative of the metal, for example, an oxid, uncombined wtih another metal, to the reactionmixture.

The combined compounds may be formed by precipitation froma solution of a derlvative of one of the metals by a salt or compound ofv the other metal. If any extra quantity be required of one of the compounds, it may be additionally precipitated from solution, together with the com ound precipitate, for the purposeof producing an almost molecularly intermixed product.

The present invention is particularly applicable to the production of ferro-alloys, such, for example, as form the bases for tungstem; chromium, vanadium, and molybdenum ferro-alloys, high speed steels, etc. In such alloys it is necessaryto introduce into the iron basisthe various'hardening Specification of Letters Patent.

Application filed June 21, 1919. Serial No. 305,869.

metals, viz :-tungsten, chromium, vanadium, molybdenum or manganese, in the desired proportions, while limiting carbon and silicon to the necessary fractional amount and insuring the practical absence of sulfur and phosphorus. v a

In the alumino-thermic process .for the production of ferro-alloys ithas hitherto been usual to add to forge scale or mill scale, or other oxid of iron, the oxids of the alloying elements as independent or separate ingredients, together with the requisite quantity of thermo-reducing agent, such as aluminium powder, the whole being well mixed previous to the reaction. Alternatively, certain of the oxids with their due proportion of intermixed aluminium have been introduced continuously or intermittently into the main bulk of the oxid of iron, during the reaction. This procedure, however, results in certain difiiculties, such as lack of uniformity of product, varying losses of the alloying metals-due to their partial volatilization at the high temperatures attained, or by their oxids passing in undue quantities into the resulting slag. By employing theprocess according to the present invention in which compounds of metals to be alloyed are chemically combined together, it is found that the metals existing in such combination tend to enter into the final alloy with greater facility and with less loss than if their oxids were added as separate powdered ingredients.

It has been further found that by employing metals in a chemically combined form according to the present invention, in certaincases the process provides an easier procedure for limiting or eliminating the silica which frequently accompanies the more acidic oxids as prepared from their ores; such silica, if present in the aluminothermic charge tends to be reduced to sili-,

-con, which may thus enter the final alloy in undesirable proportions. The preparation of silica-free tungstic acid from wolfram ores. or concentrates by the ordinary method of, fusion with soda ash is a lengthy and expensive operation, especially if it is desired to utilize the tungsten contents of such ores with completeness as certain amounts of metatungstates are always produced. But if the tungstate of sodalbepre pared from finely ground Wolfram concentrates, by digestion with strong-caustic soda solution, only the normaltungstate is produced; if this be then precipitated by the addition of the equivalent of a chromium salt or partially by an iron salt, the resulting tungstate precipitate will be practically'free from silica, and the utilization of the tungsten content of the original wolframite ore will approach completeness. Moreover the precipitation of the tungstic acid in combination with a basic oxid is more complete, and more easily performed, than is the precipitation of tungstic acid per 86 by the addition of a suitable mineral acid to a sodium tungstate solution. This method also avoids the possible formation of silico tungstates, which would otherwise carry silicon into the molten alloy. The invention is therefore particularly applicable to the production-of tungsten-containing alloys.-

A process has been proposed for increasing the yield of chromium in the aluminothermic production of ferro-chromium from chrome iron ore, which consists in adding oxid of chromium to the mixture of chrome iron'ore and reducing metal, but such process must not be confused with that of the present invention. Natural chromite is not the type of compound that we-employ as we always make use of pure compounds. Naturally occurring substances, such as chrome iron ore, are always impure, and are rarely of constant composition. They are, therefore, wholly unsuitable for the purpose of our invention, according to which the proportions of the constituents of the alloy are easil regulated and the introduction therein rom the initial materials of undesirable impurities is readily avoided. The expression pure compounds is, however, to be understood to include compounds simply free from substances whieh are not desired in the alloy and which may enter the latter during the reduction process. Thus, for the purposes of this invention the expression comprises a compound which may contain another substance (or substances) which simply passes into the slag during the reaction, or if introduced into the alloy would not be detrimental thereto or adversely affect its production.

The oxid combinations employed are combinations of the more acidic oxids with the more basic oxids:Thus tungstic, vanadic,

or molybdic acids may be combined with chromic, manganous or ferrous oxids.

.As an example of the process according to the present invention it may be desired to produce a high speed steel having the following composition Iron 77.5%

Chromic ditungstate (Cr O (W0 Q) is one of the most readily prepared compoundsof tungstic and chromic oxids, and contains chromium and tungsten 1n the ratio of 52 2184, or about 1-3V whereas the ratio between these metals required, in the alloy is 3.5 :17, or about 1:5. The balance of the WO requiredmay be combined with another basic oxid, and forthis purpose ferrous or ferric oxids are employed, preferably the former, iron being the preponderating metal of the alloy required.

The chromic ditungstate may be repared by precipitation from a solutlon 0 sodium tungstate with chromic sulfate (or chrome alum) together with an equivalent of soda ash. The remaining quantity of sodium tungstate necessary to supply the balance of the tungsten required in the alloy may be precipitated as ferrous tungstate by a solution of ferrous sulfate. quired may be employed in the form either of ferrous pr chromic yro-vanadate, which may be prepared by similar double decom- 'position methods. If a chromic salt be used The vanadium refor this purpose, a correspondingly larger proportion of ferrous salt to satisfy the re- I quirement of the increased amount of sodium tungstate-left unsatisfied bychromium will be required.

The carbon required in the alloy may be added in various ways. For instance,- a portion of the iron for the ferro-alloy may be added as scrap metal of suitable'composition thus enabling the carbon to be added partially, not wholly, in the form of carbid carried by the iron so added, or a special 'form of iron high in carbon particularly manufactured for this purpose may be added in such proportion as to .produce a content of carbon in the finished alloy that may be desired, or steel scrap of high. carboncontent or other form of iron scrap may be employed as an ingredient of the alloy producing mixture, the high reduction heat of the balance of the iron oxid and the alloying oxid being sufficient to melt the added proportion of scrap or other metal and to alloy it thoroughly with the other reduced metals on being poured on to same. Care must of course be taken that the quan-' tities of the ferrous ingredients are so proportioned as to produce a'melt at the temperature requisite to insure this.

The remainder of the iron is introduced into the mixture as forge scale or other cheap oxid of iron.

The complete m1xture of metal compounds and aluminium powder is ignited in the usual way, and the molten alloy produced. I

If nickel be the chief component of the alloy to be produced, and if in the other alloying metals (employed as. ingredients in oxid form) the acidic oxids are 'in chemialloy are a intimate mixture. In all cases the product cal excess of the basic oxids, nickel oxid is precipitated with these in the proportions necessary to combine with 'the excess of acidic oxids, since nickelis the preponderating metal in the alloy. -The balance of the nickel, forming the basis of the alloy, might be suitably added in -other forms, even partially as the metal.-

If molybdenum be the acidic oxid metal, or if nickel be the more basic oxid metal required for any given alloy, the same general method above outlinedwill be followed; for example double decomposition between a soluble alkali molybdate. and a soluble nickel salt (such as the sulfate) whereby an insoluble combination of molybdic acid and nickel oxid is thrown down.

In all cases the soluble products of the pre cipitation reaction, for example sodium sulfate, are removed from the precipitated compounds by thorough washing, and the insoluble product required as an ingredient is dried and rendered anh drous.

If desired, an alloy carrying high percentages of the alloying metals may be prepared according to the present invention, which alloy can thereafter be added to a mass of molten steel or the like in quantity requisite to produce any desired composition of final alloy.

Inroducing steel,'a molten alloy of iron and t e other metals may first be made, and the carbon added to the melt as high carbon 11011.

If the metal proportions required in the such as not to be met by the direct employment of definite chemical combinations if compounds of the metals, the excess of any metal required may be precipitated,

for example as oxid or hydrate, with thechemically combined compounds so as to secure an almost molecularly intermixed product of the desired composition, or to the moist chemical combination of any given compounds the excess of the necessary compound maybe well stirred in to produce an .-must, of course, be completely dehydrated before using it as an ingredient of the alumino-thermic or like reduction charge.

In order to introduce vanadium and molybdenum, compounds of these metals would, according to the present invention be introduced into the charge mixture in the forms, for example, of ferrous vanadate, or chro-' mium vanadate, or chromium molybdate, according to the nature and metalsrequired in the resu ting alloy.

Taking tungsten and chromium as ty es of' the metals which it is desired-to al oy with, for example, iron, our improved proc-.

ess offers advantages over those hitherto used in the alumino-thermic production of the alloy. Not only is the a1loy,'substantially free from silicon, more readily and mmercentage of .the

pletely produced, but the losses in tungstic acid and chromium sesqui-oxid when added as. chromium tungstate are reduced. The process enables auniform range of alloy throughout a series of operations to be secured.

It is to be understood that methods for producing the various combinations between the metallic compounds form no part of the present invention, but that we may use all such compounds as may be required to secure the objects of our invention.

What we claim as our invention and desire to secure by Letters Patent is 1. The process for the production of alloys'by high temperature thermo-reduction, which comprises mixing a thermo-reducing agent with a compound of certain metals required in the alloy, adjusting the quantity of one of the metals above that in combination by adding a compound of that metal with another metal required in the alloy, and igniting the mixture to reduce the compounds to the metallic "state.

2. The process for the production of alloys by high temperature thermo-reduction, which' comprises mixing a thermo-reducing agent with a compound of certain metals required in the alloy, adjusting the quantity of one of. the metals above that in combination by adding a compound of that metal with the preponderating metal required in the alloy, and igniting the mixture to reduce the compounds to the metallic state.

3. The process for the production of alloys by high temperature the-rmo-reduction, which comprises adding a derivative of one required metal to a solution of a derivative of a second required metal to precipitate a combination of metallic compounds, adjusting the quantity of one of the required metals by precipitating it with the compound of a third required metal,'is(.at-

ing the two compounds, drying them, mixing them together with a thermo-reducing agent, and igniting the mixture to reduce the compounds to the metallic state.

i 4. The process for the production of.

alloys by high temperature thermo-reduction, which comprises adding a derivative of one required metal to a solution of a derivative of a second required metal to precipitate a combination of metallic compounds, adjusting the; quantity of one of the required metals by precipitating it with the compound of the required preponderatreduction mixture containing pure synthetic combinations of compounds of metals required in the alloy, and igniting the mixture to produce the alloy by high temperature thermo-reduction.

- 6. The herein described process for the manufacture of alloys containing high melting-point metals, which comprises preparing pure chemical combinations of coming a reduction mixture containing said synthesized products and igniting the mixture to produce the alloy by high temperature thermo-reduction.

8. The herein described process for the manufacture of alloys containing high melting-point metals, which comprises preparing 4 pure chemical combinations of oxids of.

metals required in the alloy, making a reduction mixture containing said synthesized products, and igniting the-mixture to pro- I 'duce the alloy by high temperature thermoreduction. A

9. The herein described process for the manufacture of alloys containing high melting-point metals, which comprises preparing pure chemical combinations of oxids -of metals required in the alloy, making a reduction mixture containing metallic aluminium and said synthesized products, and igniting the mixture to produce the alloy by high temperature thermo-reduction.

10. The herein described process forthe manufacture of alloys containing high melting-point metals, which comprises preparing .pure chemical combinations of compounds of metals required in the alloy, making a reduction mixture containing said synthesized products, adjusting the quantity of one of the metals above that in combination by adding to the-reduction mixture a compound of that metal with the preponderating metal of the alloy, and igniting the mixture to produce the alloy by high temperature thermo-reduction.

11.- The herein described process for the manufacture of alloys containing high m'elting-point metals, which comprises adding a derivative of one metal to a solution of a derivative of another metal in order to precipitate a compound of the two metals, iso lating the compound, drying it, making a reduction mixture containing the same, and

' igniting the mixture in order to produce the alloy by high temperature thermo-reduction. 12. The herein described process for the metals, by precipitating it with a compound of a third required metal, isolating the two compounds, drying them, making a reduction mixture containing the same, and igniting the mixture to produce the alloy by high temperature thermo-reduction.

13. The herein described process for the manufacture of alloys containing high melting-point metals, which comprises adding a derivative of one metal to a Solution of a derivative of another metal in order to precipitate a compound of the two metals, adjusting the quantity of one of the required metals by precipitating it with a compound of the preponderating metal of the alloy, isolating the compounds, drying them, making a reduction mixture containing the same, and igniting the mixture to produce the alloy by high temperature thermo-reduction.

'14. The herein described process for the manufacture of ferro-chromium-tungsten alloys, which comprises making a reduction mixture containing iron and a synthetic chromium tungstate, and igniting the mixture to produce the alloy by high temperature thermo-reduc'tion;

15. The herein described process for the manufacture of ferro-chromium tungsten alloys, which comprises precipitating a solution of a soluble tungstate with a chromium salt, isolating the precipitated compound, drying it, making a reduction mixture containing the same and iron, and igniting the 105 mixture to. produce the alloy by high temperature th'ermo-reduction.

16. The herein described process for the. manufacture of ferro chromium tungsten alloys, which comprises precipitating a solution of a soluble tungstate, in part with a chromium. salt and in part with a salt of iron, isolating the preclpitated compounds, drying them, making a reduction mixture containing the same, and igniting the mixture to produce the alloy by high temperature thermo-reduction.

17. The herein described process for the manufacture of alloys containing high melting point metals, which comprises the preparation of a pure chemical combination of compounds of a plurality of metals to be alloyed, mixing a thermo-reducing agent therewith, and igniting the mixture to produce the alloy by high temperature thermoreduction 18. The herein described process for the manufacture of alloys containing high melting point metals free from objectionable impurities, which comprises the preparation of a pure synthetic combination of compounds of a plurality of the metals to be alloyed, mixing a thermo-reducing agent therewith, and igniting the mixture to produce the alloy by high temperature thermo-reduction. 19. The herein described process for the manufacture of alloys containing high melting point metals, which comprises the preparation of a pure chemical combination of compounds of a plurality of the metals to be alloyed, adjusting the quantity of one.ofsaid metals above that in the combination by adding a compound of that metal with another metal required in the alloy, mixing a thermo-reducing agent therewith,.and igniting the mixture to produce the alloy. by high temperature thermo-reduction.

20. The herein described process for the manufacture of alloys containing high melting point metals, which comprises the preparation of a ure chemical combination of compounds 0% a plurality of the metals to be alloyed, adjusting the quantity of one of said metals above that in the combination by adding a compound of that,metal with the preponderating metal required in the alloy, mixing a thermo-reducing agent therewith, and igniting the mixture to produce the alloy by high temperature thermoreduction.

In testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses.

HENRY LIVINGSTONE SULMAN.

WILLIAM BOWMAN BALLANTINE.

Witnesses:

W. H. BALLANTYNE, HARRY L. GADY. 

